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the quantitative evaluation of fringe dynamics were presented. A protocol for the adjustment and calibration process was developed to characterize various degrees of freedom of the lithography head. Starting with the determination and alignment of the fringe orientation c, thewriting pattern was aligned so that the fringes were parallel to the scan direction, thus ensuring good contrast during exposure in photo resist. Subsequently, the fringe period p = 558.2 nm(± 1 nm) could be determined by measuring the fringe displacement. Furthermore, the tilts of the writing pattern b x, y were characterized via aerial images and quantified by high-resolution measurements along the focus of the exposure beams with a tilt of 1.894 °. Subsequently, the positioning error during the scan-and-stitch process was determined. For this approach, a classic SBIL trajectory was traversed with the observation system and the recorded fringe pattern was analyzed using the carrier-frequency method. With 75 nm peak-to-valley and an RMS of 15.6 nm the errors lead to observable deviations in each individual scan line. Finally, initial exposure tests were carried out in positive photo resist to demonstrate the successful calibration and adjustment of the lithography head. The photo resist was exposed at different scanning velocities, and it was observed that the ridges of the linear structures exhibited no material loss, indicating an optimal contrast of the exposure pattern. Furthermore, the structural period was determined to be p = 556.7 nm(± 3 nm), which is in excellent agreement with the measurements obtained using FrObSy with p = 558.2 nm(± 1 nm). In future work, the FrObSy will be employed to calibrate an in-situ feedback and compensation system for the presented lithography head. All relevant degrees of freedom will be detected and the corresponding control loops will be designed accordingly. This approach aims to minimize the positioning errors identified in this study and thereby significantly improve the fabrication of linear gratings using SBIL.
Acknowledgments
We would like to thank Holger Ruehl for his assistance in characterizing the exposed gratings.
Funding
This work was supported by the German Research Foundation( Deutsche Forschungsgemeinschaft, DFG), grant no. 465642714. The nanopositioning and measuring machine NPMM-200 was funded by the Deutsche Forschungsgemeinschaft( DFG, German Research Foundation) – 267094782.
Conflicts of interest
The authors declare that they have no competing interests to report.
Data availability statement
Data underlying the results presented in this paper are not publicly available at this time but may be obtained from the authors upon reasonable request.
Author contribution statement
Conceptualization K. T., J. R., I. O., C. P., T. H., O. S., E. M., T. K. and S. R.; Methodology C. P., T. H., O. S., E. M., T. K. and S. R.;
Software, K. T., I. O. and J. R.; Investigation K. T., J. R., I. O. and C. P.; Writing – Original Draft Preparation K. T.; Writing – Review Editing K. T., J. R., I. O., C. P., T. H., O. S., E. M., T. K. and S. R.; Project administration T. H., O. S., E. M., T. K. and S. R.; Funding acquisition T. H., O. S., E. M.
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